Within-plant distribution of the western flower thrips (WFT), Frankliniella occidentalis, was determined in a greenhouse crop of garden impatiens, Impatiens wallerana.
Impatiens flower bud development was divided into five arbitrary stages, designated A–E, with stage A representing tightly closed buds and stage E representing opened flowers. Numbers of each thrips life stage among these flower stages was determined at six times daily. Distribution of all thrips life stages was also determined among flowers with pollen, flowers with pollen removed, and on budless stems, at two different times of the day (08:00 and 00:00h). Terminal 7–cm sections of foliage from a crop of budless impatiens were sampled five times daily, and the number of each thrips life stage was tallied. Each successive stage of flower, contained significantly more adult female and immature thrips than the previous stage. Stage E buds contained significantly fewer adult female and immature thrips than stage D buds. There was little effect of time on thrips density across flower stages, however flowers with pollen had significantly more thrips than flowers without pollen at 00:00 than the other sample times. Flowers with pollen had significantly more adult females and males than flowers without pollen, but numbers of immature thrips were not affected by presence of pollen. Flowers with and without pollen contained significantly more immatures than foliage. Foliage sampled in a flowerless crop showed no effect of time of sample on thrips density.
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